Electric pull switch



zeb l2 ,1924.9 1,483,584 Y T. J. KERWIN v ELECTRIC PULL SWITCH Filed Reb. 23 1922 lllll Patented Feb. l2, E924..

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THOMAS J. KERWIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO EDIVIUNDS & JONES CO- PORATION, A CORPORATION OF NEW YORK.

ELECTRIC PULL SWITCH.

Application led February 23, 1922. Serial No. 538,499. t

To all whom It may concern: Be it known that l, THOMAS J. KERWIN, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Electric Pull Switches; and l'do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertai'ns to make and use the same.

My invention relates to electric switches and in its general aspects aims to provide a simple, cheaply constructed and easily wired switch adapted for normally maintaining an open circuit and for closing the circuit upon movement of its operating member in one direction.

In using signal lamps for various purposes, such as the 'so-called stop lights now employed at the rear. of automobiles, it is customary to have the circuit to the lamp or other signal normally open and to have this circuit closed by the movement of an operating switch member which is normally held in its circuit-opening position by a spring. For such purposes, it'is desirable that the closing of the circuit by the switch should be eEected upon a predetermined movement of the operating member and that this operating member should be permitted to move considerably further without efecting the contacts and without overstrainingl any operative part of the switch. Furthermore, it is highly desirable that such a switch should beV substantially sealed against the entrance of moisture, dust or mud, that it should be durable but inexpensive, and that the needed connections to the circuit should readily be made from the exterior of the switch.

My present inventionaims to provide a switch construction meeting these requirements and one which might be equally suitable or other uses where the operative condition of a circuit is to be altered by the movement-of an operating member which is yieldingly urged at all times towards a predetermined position. More particularly, my

inventionaims to provide a switch for this purpose in which the switching member comprises a resilient contact member adapted by its own resiliency to bridge across the wire terminals of the switch, and in which the opening of the circuit is effected by interposing an insulating element between one end of the contact arm and another portion of the switch. llt also aims to provide an unusually simple and effective mounting for `such an insulating element, desirably in the form of a stem projecting slidably through and from the accompanying drawings, i y

which p I Fig. l is an elevation of a pull switch embodying my invention.

Fig. 2 is a plan view of the same.

Fig. 3 is a bottom view of the same.

Fig. 4 is an enlarged plan view of the switch with the cover plate removed.

Fig. 5 is a vertical and longitudinal section through the switch, taken along the line 5-5 of Fig. 4.

Fig. 6 is a. transverse section taken along the line 6 6 of Fig. 4.

Fig. 7 is a perspective view of the insulating contact lifter and of the guide pin secured to the latter.

Fig-8. isa plan View showing the overlapping insulating base members of the switch together with the two circuit terminals and the resilient contact strip mounted on the same. A

In the embodiment of the drawings, the housing of the switch consists in an elongated metal casing of substantially rectangular transverse cross-section, lwhich casing desirably has its main portion formed from a single piece of sheet material and has at each side of its upwardly directed mouth an ear 1, the two ears being disposed substantially in a common plane. As a closure for this main casing portion I provide a cover plate X, 2, desirably having its side edges shaped to conform to those of the two ears 1 and secured to both of the ears by eyelets 3 extending through alined perforations in'the ears and cover plate and clinched over both thereof. When both eyelets are thus inserted, they hold thel cover .in a tightly closing position and also afford perforations for the screws such as a switch is commonly fastened to a suitable support, such as the bottom of the floor of an automobile.

Seated on the bottom 4 of the casing is an insulating base which desirably consists of a lower plate 5 shaped to abut against the lateral and end walls of the casing so as to form an insulating lining for the bottom of the casing, and a narrower insulating plate 6 superposed on this bottom plate 5. Extending through both of these insulating plates are a pair of screws 7 and 8, each of which extends through a considerably larger perforation in the bottom of the casing and each of which has a pair of nuts 9 threaded thereon outside of the casing. In each case an insulating washer 1() is disposed between the upper nut and the bottom of the casing so that one of the circuit wires 11 or 12 can readily be clamped by the upper nut against this-insulating washer, after which the lower nut can `be tightened on the corresponding screw to serve as a lock-nut.

Thus arranged, the two screws 7 and 8 form terminals of the circuit and simultaneously clamp the two insulating plates and the ends of the circuit wires firmly in position. One of the said screws` namely the screw 7 in the embodiment of the drawings, `also extends through a perforation in one end of a contact member 13 made ofa resilient metal (such asphosphor bronze) and so formed that itsown resiliency will normally force its other end down upon the head of the companion screw 8. This contact member also has an arm 14 extending laterally from its free end, so that thisl arm will overhang the lower insulating plate 5 but will be spaced from the latten by the thickness of the upper insulating plate and theradded thickness of the screw 8.

To raise the contact member out of engagement with the screw 8 when the circuit is to be opened, I provide a member movable within the casing and having a portion adapted to be interposed between the arm 14 of the contact member and the lower insulating plate. For this purpose. I desir- "-ably employ an insulating head 15 in the lower insulating plate 5 and the cover 2 of the casing, so that this insulating head is slidably guided by the said cover and insulating plate. The head 15 is notched 'from the edge facing the nearer end 6 of the casing so as to afford a lower wedge-shaped portion 17 adapted to be slid under theoverhanging arm 14 to lift this arm sufficiently to bring the contact member" 13 out of engagement with the head of the screw 8.

To operate the movable head 15 for th1s purpose, I fasten the same to a metal stem 18 extending slidably through a slot in the other end 19 of the casing and having in its exposed outer portion an eye 2O whereby this stem may be connected to a brake lever or other means for actuating the switch by a pull on this stem in a direction which is towards the left in Figs. 1, 4 and 5 of the drawings. To prevent a lateral movement of the head 15, I also provide suitable means associated with it for slidably engaging the side walls 21 and 22 of the casing and for this purpose desirably employ a guide pin 23 driven tightly through a corresponding bore in the head 15 and extending through a corresponding bore in the stem 18. Thus arranged, the stem 18 with the head 15 and the guide pin 23 rigidly secured to the same form the operating member of my switch. Then I also provide yielding means for normally holding this operating member in a predetermined position, desirably by slipping a spiral compression spring 24 over the stem 18 so as to interpose this spring between the end 19 of the casing and the head 15 on the operating member.

With the switch thus constructed for use on a normally open circuit, the spring 24 normally slidesthe operating member towards the left in Fig. 4, or until the insulating head thereon abuts against the wall 16, thereby causing the wedge 17 to lift the `con tact member ofi' the head of the screw 8 as shown in Fig. 6. However, if the operating member is pulled towards the left of Fig 4 against the pressure of the spring, the resiliency of the contact member 13 will flex the latter downwardly into engagement with the head of the screw 8, thereby closing the circuit., This closing of the circuit occurs as soon as thev operating member has been moved for a predetermined distance depending on the thickness and slope of the wedge portion 17 and any continued movement of the operating member in the same direction will not eii'ect the operation of the switch. Consequently, my construction is particular-ly adapted for purposes where the extent of the pull may be varied considerably.

To facilitate the assembling of the parts, I desirably fasten the contact member 13 first to the upper insulating plate 6 by a rivet 25, this being done while the contactarm is swung to a position corresponding to that shown in dotted lines in Fig. 8. 'lhenA through a perforation in the stationary end of the contact bar, so that this screw and the rivet 25 cooperate in preventing the contact bar from rotating about eithei` thereof. When the two screws are then slipped through the lower insulating plate, the lower head of the rivet 25 bears against the top of the lower insulating plate, so that the latter i insulates this rivet from the bottom of the casing. By thus forming a screw and contact assembly on the two insulating plates before slipping the latter into the casing, l simplify and facilitate the manufacture of the switch, as the resulting assembly can readily be dropped into the case and clamped in position by afixing the insulating washers 10 and the nuts 9 to the screws.

The operating member is vassembled by simply driving the guide pin 23 tightly through a corresponding bore in the insulating head 15, slippingthis pin through the corresponding bore in the bar 18 and riveting the latter to the insulating head by a rivet 27. rlhe spring 24e is then slid over the main portion of this bar, and the perorated end of the latter is slipped through the slot in the end 19 of the casing from the interior of the latter. Bythen moving the assembled operating member so that the wedge portion of its insulating head will clear the arm on the contact member, the head portion can readily be swung down into its normal position, after which the cover plate is attached by the eyelets 3.

With the switch thus assembled, it will be evident that the wiring connections are conveniently exposed on the exterior of the switch so that the casing does not need to be opened Jfor this purpose but can be leftclosed at all times. ln operation, the slot through which the stein 18 projects guides the outer end of the latter, while the head of the operating member is guided atits top by the cover plate and at its bottom by the lower insulating plate or bottom lining and is also guided laterally by the sides 21 and 22 of the casing. Moreover, the upper. insulating plate 6 may also be made of such a width as to engage one face of the head 15 so as to forni 'an additional lateral guide for the latter as shown in the drawings.

However, while l Vhave illustrated and described my invention in an embodiment in which the retracting spring normally holds the switch in a circuit-opening position and one including various desirable details of construction suitable .for a particular purpose, l do not wish to be limited in these respects. Obviously, the switch ot my invention might also he employed for other purposes, while the construction and arrangement might be varied in many respecta without departing either from the spirit of umy invention orY from the appended claims.

l claim as my invention 1. An electric switch including an elongated casing of rectangular section, an operating member movable longitudinally thereof and having a head'slida ly engaging two opposed longitudinal walls of the casing, and a guide pin'fast upon and extending transversely of the head and slidably engaging the other two longitudinal walls of the casing.

2.. In Aan electric switch, an elongated casing, an insulating lining for a longitudinal wall thereof, a pair of wire terminals mounted on the insulating lining, a resilient contact member fastened to one terminal and yieldingly forced by its own resiliency into engagement with the other terminal, and a separator of insulating material slidably disposed between the said insulating lining and the opposite longitudinal wall of the casin and formed for forcing the contact mem er out of contact with the said other terminal when the separator is at the end of its slidable movement in one direction, the insulating lining having a shoulder formation extending longitudinally of the casing for laterally guiding the separator.

3. A' contact separating member for a switch having a pair of yieldingly engageable contacts, comprising as one element an insulating head having a wedge portion arranged for moving one of the contacts, and as another element a stem fast on the said head, and a guide pin fast on one ofthe said elements.

a. A contact separating member for a switch. having a pair of yieldingly engageable contacts, comprising a Hat insulating head having a tapering notch at one end to provide a wedge formation, the wedge formation being arranged for moving one contact away from the other, a dat stem fast on the head, and a guide pin fast with respect to both the head and the stem and extending transversely of both of the latter.

5. A Contact separating member for a switch having a pair of yieldingly engage-v able contacts, comprising a iiat insulating i head having a wedge portion arranged for moving one contact away from the other, a stem fast at one end upon the head, a casing housing the said contacts and separator, and spring means continuously urging the separator in one direction and normally forcing the insulating `head against one end oit the casing. l

6. A contact assembly for an electric switch, comprising a pair oi superposed insulating base members, a pair of circuit terminal screws each extending through both base members and presenting heads on the upper member, a resilient Contact strip clamped at one end against the upper base member by one of the screw-heads and 5 having its other end bearing against the other screw head, and a rivet securing the Contact strip to the upper base member at a point between the two screw heads, the rivet terminating above the lower base member. I

Signed at Chicago, Illinois Feb. 18th, 1922.

'THOMAS J. KERWIN. 

